The duct furnace shall be installed on the positive pressure side of the circulating air blower.
Means shall be employed on these lines to prevent water from entering and to prevent blockage by insects and foreign matter. An atmospheric vent line shall not be required to be provided on a valve train component equipped with a listed vent limiter.
[M] TABLE 622.214.171.124
DRYER EXHAUST DUCT FITTING EQUIVALENT LENGTH
|DRYER EXHAUST DUCT FITTING TYPE||EQUIVALENT LENGTH|
|4 inch radius mitered 45-degree elbow||2 feet, 6 inches|
|4 inch radius mitered 90-degree elbow||5 feet|
|6 inch radius smooth 45-degree elbow||1 foot|
|6 inch radius smooth 90-degree elbow||1 foot, 9 inches|
|8 inch radius smooth 45-degree elbow||1 foot|
|8 inch radius smooth 90-degree elbow||1 foot, 7 inches|
|10 inch radius smooth 45-degree elbow||9 inches|
|10 inch radius smooth 90-degree elbow||1 foot, 6 inches|
Exception: This section shall not apply to one- and two-family dwellings.
Exception: The minimum volume requirement shall not apply where the amount of return air taken from a room or space is less than or equal to the amount of supply air delivered to such room or space.
Exception: This shall not apply where:
Floor-mounted-type unit heaters shall be installed with clearances to combustible materials at the back and one side only of not less than 6 inches (152 mm). Where the flue gases are vented horizontally, the 6-inch (152 mm) clearance shall be measured from the draft hood or vent instead of the rear wall of the unit heater. Floor-mounted-type unit heaters shall not be installed on combustible floors unless listed for such installation.
Refrigerators shall be provided with adequate clearances for ventilation at the top and back, and shall be installed in accordance with the manufacturer’s instructions. If such instructions are not available, at least 2 inches (51 mm) shall be provided between the back of the refrigerator and the wall and at least 12 inches (305 mm) above the top.
Air-conditioning appliances installed in rooms other than alcoves and closets shall be permitted to be installed with reduced clearances to combustible material, provided that the combustible material is protected in accordance with Table 308.2.
Where the air-conditioning appliance is installed within a space separated from the spaces served by the appliance, the air circulated by the appliance shall be conveyed by ducts that are sealed to the casing of the appliance and that separate the circulating air from the combustion and ventilation air.
|CHIMNEY HEIGHT (feet)||MINIMUM PERMANENT FREE OPENING (square inches)a|
|Appliance input rating (Btu per hour)|